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hoyas

Bringing Back the Hoya

For many of us, hoyas are those plants our grandmothers had growing on the ‘stoep’ or in a pot that hung from the dining room ceiling in a macramé pot hanger.

The genus Hoya contains between 200 and 300 different species. In addition, there are also lots of hybrids and cultivars of certain species, making it an incredibly diverse group of plants. Hoya plants go by numerous different names: wax flower, wax plant, wax creeper, wax vine, porcelain flower and Mary’s tears, to name just a few. These plants have a home range that stretches from India in the west to China in the east, and reaches downward through Thailand, Vietnam and Malaysia, through all the Southeast Asian islands and even extends to the northern parts of Australia. Because of this wide distribution range, which includes many different habitats, these plants have varying growing requirements, which we need to keep in mind when we want to keep them here in South Africa.

In general, most of the hoyas can be described as tropical, while certain species are subtropical. The subtropical species are the easiest to grow in our climate, as the tropical ones need high temperatures coupled with high humidity throughout the year to perform at their best. The growth habits of the different species vary greatly, but most can be classified as twining climbers that in some cases produce roots along the twining stems to adhere to the bark of trees or rocks the plants are climbing on.

Some hoya species form more of a scraggly bush. Many of the species will grow in the soil or in leaf litter and then climb up a tree, or as an epiphyte on the tree. There are a few species of hoya that are almost leafless, others have extremely tiny leaves, while the leaves of a species such as the aptly named Hoya macrophylla can reach gigantic proportions of up to 30cm in length. The leaf surfaces can be waxy, velvety, grainy, glossy, warty, glabrous, and the list goes on. Most of the leaves will be green (they come in many different shades) and some will have cream or white speckling, spotting or blotching.

There are leaves with lighter or darker coloured veining, while some have maroon, pink or reddish veins, speckling, splashes or edging. Many variegated forms of the species are also sought after. Flowers can be carried singly on an inflorescence or in huge clusters forming a round ball, and just about everything in between. The range of colours in the flowers is astounding. Many flowers have a shiny, waxy (as their common name suggests) appearance, but some species have flowers that seem to change colour due to their velvety texture. Most hoya species are fragrant and produce copious amounts of nectar that drips from the flowers in certain species, which is where the name ‘Mary’s tears’ comes from.

People grow hoyas for different reasons. Some grow hoyas as indoor plants for their lovely cascading habit and lush leaves. Some collectors grow hoyas for the different leaf shapes and patterns, while others look for certain traits in the flowers. Whatever your reason for growing hoyas, they are truly rewarding plants that in many cases prosper even with very little care and attention. For beginners, the easiest of the hoya species to grow would be Hoya carnosa and Hoya pubicalyx. Hoya carnosa is in most cases the plant that your ‘ouma’ had on her ‘stoep’. There are many different colour forms of these species, as well as varieties with different shaped and coloured (variegated) leaves.

How to grow

It is always a good idea to read up a bit about any new plant you get. In the case of hoyas, you need to research where the specific hoya you have comes from. If it is from a hot sticky jungle it will need warm, moist growing conditions, while Hoya carnosa can handle low temperatures of just above freezing. It is best to protect your hoya plants from cold winds in autumn and winter, but in the warmer, subtropical parts of the country many different hoyas can be grown outside. In other areas a sheltered patio or indoors would be best. Hoya plants need bright light but not direct sunlight. While they will be able to grow in very low light conditions, they will probably not flower in such conditions.

Many of the hoya species grow in areas where trees may lose some foliage during the drier months, allowing extra light to reach these plants. For a potting medium use a mixture of coconut chunks with some added perlite. Coarse peat also works very well as a potting medium. The idea is to keep the roots moist but not continually wet. The plants benefit from regular applications of water-soluble fertiliser. Unfortunately, hoya plants are quite susceptible to mealybug infestation so you must check the leaves for these critters on a regular basis. Improving air flow around your plant will also help prevent mealybug issues.

Hoya bella is one of the species that does not creep but rather forms a scraggly bush, often hanging. The pure white flowers have a magenta pink corona in the centre.
Hoya linearis has a pendent growing habit. The stems and hairy rounded leaves hang down like a curtain, while the creamy white flowers face downward.

Heart-shaped hoyas

One of the plants that is able to root from just a leaf is the humble Hoya kerrii. Hoya kerrii produces beautiful heart-shaped leaves, which has led to single leaves of Hoya kerrii being potted in a small pot to sell as a cute Valentine’s Day gift. The leaves root, and these roots can sustain the leaf for many years. If the cutting does not include part of the stem and an eye, it will never produce any further growth. Sometimes an eye is included in the cutting and the person is lucky enough to have the little leaf eventually produce a stem and new plant.

Some of the species with interesting leaves include Hoya fusco-marginata, Hoya imbricata, Hoya caudata, Hoya globulosa and Hoya polyneura to name a few.
The species with the largest flowers are Hoya imperialis, Hoya macgillivrayi, Hoya mappigera and Hoya lauterbachii. These are unfortunately all very tropical and therefore cold sensitive.